Distinct passenger strand and mRNA cleavage activities of human Argonaute proteins

Bingbing Wang, Shuqiang Li, Hank H. Qi, Dipanjan Chowdhury, Yang Shi, Carl D. Novina

Research output: Contribution to journalArticle

94 Scopus citations

Abstract

Argonaute (AGO) proteins bind to small RNAs and mediate small RNAinduced silencing in eukaryotes. Using a minimal in vitro system, we show that bacterially expressed human AGO1 and AGO2 but not AGO3 and AGO4 possess strand-dissociating activity of microRNA (miRNA) duplexes. Both AGO1 and AGO2 function as RNA chaperones, capable of performing multiple rounds of strand dissociation. Unexpectedly, both AGO1 and AGO2 demonstrate passenger strand cleavage activity of a small interfering RNA (siRNA) duplex, but only AGO2 has target RNA cleavage activity. These observations indicate that passenger strand and mRNA endonuclease activities are mechanistically distinct. We further validate these observations in mammalian extracts and cultured mammalian cells, in which we demonstrate that AGO1 uses only miRNA duplexes when assembling translational repressioncompetent complexes, whereas AGO2 can use both miRNA and siRNA duplexes. We show that passenger strand cleavage and RNA chaperone activities that are intrinsic to both AGO1 and AGO2 are sufficient for RNA-induced silencing complex (RISC) loading.

Original languageEnglish (US)
Pages (from-to)1259-1266
Number of pages8
JournalNature Structural and Molecular Biology
Volume16
Issue number12
DOIs
StatePublished - Dec 1 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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